1. Field of the Invention
The present invention relates to a joint structure by which the trailing arm of an independent rear suspension is coupled to a knuckle in a motor vehicle such as an automobile.
This application is copending with related and commonly assigned U.S. patent application Ser. No. 653,644 filed Sept. 24, 1984. Note, however, that such application is directed to novel subject matter which is patentably distinct from the subject matter of the present application.
2. Discussion of Relevant Art
Japanese Laid-Open Patent Publication No. 60-67203, filed on Sept. 22, 1983 and published on Apr. 17, 1985, discloses an independent rear suspension composed of a trailing arm, an upper arm, lower arms, and a correcting link, the trailing arm being sufficiently resilient in the transverse direction of the vehicle frame and highly rigid in the vertical direction. The disclosed trailing arm is composed of a leaf spring and has a front end vertically pivotally coupled to the vehicle frame by a rubber bushing. The rear end of the trailing arm is fastened by bolts to a knuckle arm. A wheel is rotatably supported on a spindle projecting outwardly through the trailing arm. The upper and lower arms which extend inwardly of of the vehicle frame have outer ends coupled to the upper and lower ends of the knuckle arm.
Since the trailing arm is resilient transversely and rigid vertically, the amount of transverse movement of the rubber bushing on the front end of the trailing arm is reduced for reducing resistive forces against the vertical movement of the trailing arm, resulting in improved riding comfort and noise reduction.
Because the knuckle is coupled to the inner surface of the rear end of the trailing arm, however, the trailing arm is required to be of an elongate configuration including the portion which supports the entire back of the knuckle. As a consequence, the requirement for the trailing arm to be elongate in shape has posed certain limitations on efforts to reduce the weight and cost of the trailing arm. Furthermore, inasmuch as the lower arms are connected to the lower end of the knuckle, it has been tedious and time-consuming for the worker to join the lower arms to the knuckle, especially to install bushings between the lower arms and the knuckle. Additionally, if the buckling strength of the trailing arm which is subject to compressive and bending loads were to be increased by increasing the thickness thereof, the rigidity of the trailing arm compared to its ability to flex would also be increased to the point where the desired function of the leaf spring serving as the trailing arm would not be attained.